Attachment means for lamination panels



May 26, 1959 yG. E. KLooTE Erm. 2,887,732y

ATTACHMENT MEANS FOR LAMINATION PANELS l Fned Feb. 2. 1956 LINVENTORSJOSEPH A. POTCHEN GEORGE E. KLOOTE GEORGE D. MEIER A'TTORNEY United Se@`aser/,732 TQ ATTACHMENT MEANS FORA LAMINATION --yPANELsf This inventionrelates to la.' means of attaching'to'gether 15 two angulaily disposed,laminated panels made entirelyg'o' largely of synthetic resinmaterial,`v particularly those'hav'` i ing a lowdensity'coreandahardfacing sheet. V v Serious trouble sometimes occursinljining two nated panels atan angle to Ieach other'. This isespecially 20 true when the'panelsare fabricated ofa hard-Ffacingf'ad acoreofa low density material, such as affoa'med'polyf styrene, 'foamedphenolic-'or a foamedfpolyisocyanate-.f Such core material is'Icomparatively` weak' in tension(A As aresula' the facing sheet may peelolf, especially/"if anA 25 edge oflthe Asheet works loose or an `'objecthooks'L under the edge.` lThis type vof lcore material l'normally is nothard and readily permits penetration byafsharpobjctj Thus,it allows'anobject to hook underthle' facing sheet once'an openin'gis exposed.'v4 'i*=`f 30 gvwhere` meacrlef does not 'contain one or more laminaf woodcy'raiother` hygroscopic material, the'problernI of damage resulting'front objects becoming hooked under the edge-ofthe-facing sheet is notquite sofcriticall But; the exposure fof 'ai hygro'scopic sulvlainina`toj moisture result#` 35 ingffrom an: opening orlooseedge'fisdetrimental. I'he moisture in theistblamifna maylcausethefacitig to peel oli'. It may falsocausefdeteriorationlandwarpage of-Vthe' Wood-.1Q J 5c 1 i "uw r-. '-uf nAnotlierinportaconsideration in attach g tw'ollar'n na't'edlpanels is fthataiiyexposuure of the 'corleorfipee offthe facing gives ithe structureanuiidesirablejappeanance. Thus; itis-conventionaltofcoverItheioiritsvbistv've'en the two-panelsiwith abattingstrip' or strippingtape# This is undesirable becauseit destroysft'hes'rrioo'thand'conijinu- 45 ons fenect of `theljojirnsf Further; the stripping tpeitself; maypeel off." l t' *"Q i ltis1"the object of this `invention toprovide' *ai means' t ofattaching'tatftan"angle two`panels,"each of"said-panels being formedtof'aml'ow density fc'or'e and-'ia'har'd'facing 50 Sheet. 31:1 y ff. :i' i". ITA "-Y? Pf. Another 'object oflthis l inventionl is to provide a `inearis and a method. offjo'ining'suchpanelstogether. soias toi-give eV neat and rsmooth'fappearance; while ati-the ,same time f .'iwearwlshockwand 55 provide fawith'a 'facing sheet securedlto the ore at ofthe anglefo'rmedtliepanels, The

1' 10fach tfi' give a metterli-satana et am 'tima mangia tvforriedl,refllstfitzt aga s ng of thefacingsheets and breakage of thejennyV .These and maar evantagesand chieste-sfeer. ,invention willbecome -obvious to one skilled in;t he`,v,of, syntheticlaminatedpanelsupon readingthe following speciQatiQll, iu crliurlctiorivwith the aqc'qllpnyifns dawingawhercin: Fa 1t is :ilfragisfitafnSetinlwiew of! two'syiifhsc resin panels fjoinedtogether inaccordance XeQBR'a Patented 1 May l2 6, 1(959 y 2 t Fig. v2`isafragmentary view of the edge of one ofthe panels.Y

Fig. 3 is a fragmentary, side view of the edge of the otherpanel.v "i

Fig. 4 is'an oblique, fragmentary, exploded view of the sheetlis'secured'to the bodyat the inner sides of the angle formed betweenV thepanels.. The inner cornerconstruction includes one of the panels havingblind holes extending throughits innersheet van'dinto vits core. Theother panel has'protrusin's 'on the edge ofthe inner facing sheet.vThese-protrusions are vinserted into the holes. The

outer' corner' construction includes a bead of adhesive 1ocated in a''cavityv cut out lof the corner and extending under the outerfacingsheets of the panels. These outer facing sheets are adhesively bondedto' the bead as well as to the adjacenbsurface off'thefco're'. `Theadjacent remaining portions of v'th'e'edges' of the panels at the jointare shaped toiit each-other and are secured together by an adhesiveor'other suitable bond. v 1 Throughout this' description, the wordsinner and outerz-shall'be taken to `rnean ffinner toward the inside ofthe enclosedfangleform'ed by the intersection of the twopanels; andouter indicates the exterior angle.

'Referring specically tothe drawings, the numerals 10 and 20=ach `denotea` laminated panel. The panel 10 has a low density core 11, an innerfacing skin 13and asublamina'12, and the=outer facing skin 14. Panel 20is similarly constructed and' includes Vthe core `21,- aninner facingskin 23 and asublamina 22? and outer sheet 24.-' The panels `10 and 20are vjoined to each other at an angle.

The cores 11and 21 maybe ofany suitable type of lightweight; lowdensity; cellular 'material'. One such material is afoamed polystyrenevsuch as those made by polymerizing ahydrocarbon or`halohydrocarbonhaving a vinyl radical or an aromatic nucleus and-includes the productsresultingiffror'n polymerization of styrene, Vmonomethylstyrenevinylfnaphthalen'e-and-the halogenated styrenes. Such foamed core materialnormally has a density intherange of two to'tenJ pounds per cubic foot.'The core mayl be'foffa-foamed'infsitureaction product of apolyisocyanateandia suitable polyester or alkyd resinous composition.An'exa'mple of such a polyisocyanate isa metatolu'ene-,diisocyanate.vThis latter is but an exempliationA-becau'se other? aromatic'-plyisocyanates can be employed 'quitesatisfactorily.` The foamedphenolics, of which there `are various types, may also 'be' employed forthis"y purpose." 'Such light weight,= foamaceous, core ma'terials'fl'i'av rather poor lresistanceto tension' loading:'Ilhus,fifione endof the-'facingsheet'can be grippedand pulledf-ibak'1it-iwil'lfhave a 5 tendency to #rip loose from the core byl-tearirigth'c'or'e adjacent the bond between the -"'='l`he` inner-facing sheetsof -thepane'ls' are made of either one or-two layers. `Preferably;'twolayers' are used, con# sisting ofM anE inner lamnalzi and22 of plywoodorhardboard or :other: similar materialsl'includingf ligneous andmineraltbenmterials'bonded by "syntheticilresin or ce? mentitiousA'binderssecured tan -o'uter skin '-13' and"23'.` The 'skins .23 .are Yof faf'hard; impervious resin material" which-may betsecurelytbndedtothe sublaniinae orcorej material iby'a suitable" resin 'ofradhesivelproperties in" vwhichsneitherxthe facing sheet, tlfesublaminae or coreEare readily soluble. A suitable resin/for manufacture of the skinsfisany one vof the'` numerous; kconmrercially avai1able,. polyesteraresins.The lresin is` normallyurein# forced with at-,fibrous material tsuchlamentary -glassiV i9. Whill @S2-@libwww 1 rzieither orienteder@arrangedat random. When cured, they have a thickness normally within therange of 0.015 to about 0.060 of an inch. The sublaminae 12 and 22 maybe of the same thickness or they may be of different thicknessesdepending upon the particular requirements of the installation in whichthe panel is to be used.

It will be recognized that this invention may bev practiced with panelshaving no inner sublamina. or1no inner surface skin. It may also bepracticed with panels, having more than two inner sublaminae.

The outer facing sheet is illustratedl as consisting 4of one lamina ofmaterial similar to or exactly the same as the material of the skins 13and 23. This facingI sheetz l may also consist of two laminae includinga sublamina. of hardboard, plywood or like material and al surface. skinof reinforced, synthetic resin. j

When two lamina are utilized as either inner or outer.

facing sheets, the lamina may be bonded together pre-V Il.

viously to assembling they entire panel; or the lamina can be bondedtogether during one complete assembly of the panel. In either case thelaminae may be bonded together and the facing sheets suitably bondedtothe core with an epoxy resin adhesive hardenable at ambient ormoderately elevated temperatures and under only sufficient pressure toassure firm contact between the, elements during the curing period. Thisadhesive is the; liquid, partially polymerized, high molecularweight,ref action product of a diphenyl and anepoxy compound. One example ofsuch a reaction product is that obtained by heating together2,2"-bi(4hydroxyphenyl propane) and epichlorhydrin in the presencev ofan alkali` such as sodium hydroxide, whereby there are formed` polymericglycidyl polyethers of the phenolic substancehaving prop-y erties and anaverage molecular weight depending upon the reaction conditions and theproportions of reactants employed. This is merely an example of oneparticular adhesive and it will be recognized that various other ma-Aterials may be used without in any way affecting` this invention.

For the purpose of bonding together the various laminae making up thepanels 10 and 20, contact resins may` be used as substitutes for theepoxy type adhesive resins.. The contact resins used for this purposemust b eof a type which will adhere strongly to themselves even aftel.v

evaporation of the carrier whether it is water or a sol. vent.

Among suitable contact type adhesives for this purpose,l is D-253-20sold by Armstrongy Cork Company. 'This is a synthetic rubber basematerial containing a solvent Another suitable contact ad-f 50 andmethyl-ethyl-ketone.. hesive is EC-97l sold by Minnesota Mining andManuf facturing Company'. The latter is a watery dispersion. type ofadhesive. Other usable contact adhesivesinclude. Nos. 971, 871 and 321all sold by Minnesota, Mining and Manufacturing Company. These. arewater disperr. sion adhesives. Also usable,l is Minnesota Mining andManufacturing Companys solvent carrier contact ad..- hesive 13C-1390.These are but exemplary of thecontactf adhesives which may be used forthis purpose.

These panels are normally made by first fabricating the facing skins ashard, continuous lengths of flexible material.l By suitable equipment,the facing' sheets are, bonded one to each side of thecore material. In'the case of a foamed-in-pliace type'materialtthe. facing sheets areplaced in a suitable` machine andy the. corev material foamed betweenthem. Mostfoamed-infplace.: polyisof cyanate. materials do not requirean, adhesive since the core material. itself acts as the. bondingv agentto; the fac.-

ing sheets. The panels, as they' leave; the panel forming i process,each; have at least one exposed edge where they can be joined together.

Itv willv be recognized that although thereA are shdwn on the inner faceof each panel both askin andi a su`blamina, a. single lamina will worksatisfactorily; Also; While these@ panels are` normally :nan'factured'ywith fad-1'- 4 a ingI sheets on both sides, they may be fabricated withone on the inner side only. Various combinations of laminae of this typemay be made without interfering with the practice of this invention.This invention is applicable to any of these forms.

An exposed edge of each panel is shaped and prepared for attachment tothe complementary edge of the other l panel to which it is to be joined.This shaping and preparation can be accomplished by cutting awayportions of an` existing square edge, or the shape of the edge can beformed by a mold or otherwise. It has been found that the preferredprocedure is to form square edged panels and cut-out portions of theedge to form the desired joint. Both the facing. sheets and the corescan he` cut 15 and removed by any suitable equipment such as a router.

In forming the joint illustrated in Figs. 1 and 4, two different jointsare used, one at the outer corner 40 and the other at the inner corner50. At the outer corner 40, the core material is cut out of each panelat the point of juncture of the outer facing sheets 14 and 24. Thus, infitting the two edges together a pocket is created. This pocket isfilled with a bead 30 of adhesive material' of a type impervious tomoisture. The bead 30 adheres strongly to the core material 11 and 21 ofeach panel and the outer facing sheets 14 and 24. This provides a firmanchor at the corner for the sheets 14 and 24. The epoxy type adhesivesare par- `ticularly. suited to the formation of the bead 30. The bondformed between the epoxy type resins and the,

polyester type facing sheets is not subject to delamination under normalmechanical injury. Such a bead is `not readily subject to cracking evenunder heavy impacts. The force created by sharp, downward blows on thelcorner at the edge of sheet 24 will be distributed to the, facing sheet14 and transmitted to the cores in. shear. Since the bonds ybetween thefacing sheets and the cores are highly resistant to shear loads, theweak-4 ness of the bond under tension loading is avoided. For .thisreason, it is important that the Ibead 30 extend a short distance (from.2 to .5 inches) back under both sheets, 14 and 24. This feature issimilar to the corner construction forming the subject matter of ourco-pending7 application Serial No. 522,942, filed July 19, 1955,

which` has now matured into U.S. Patent No. 2,826,-

240, issuedI March 11, 1958. It will be recognized that the beadI 30mayl be reinforced by filamentary material such as glass. This willfurther add to its strength.

The inner corner construction includes the cut out portion or cavity 25in the edge of panel 20. Panel 10.

has an overlapping portion 15 having the same shape and size asthecavity 25 and designed to nest in such cavity 2.5 (Fig, 1). Locatedalong the juncture of the inner facing sheets of the panels are aplurality of blind holes 16 extending through the skin 13, the sublamina12 and into the core. 11. The depth of these holes is suicient toreceive the. end tenons or protrusions 26 along the edge of the facingsheet 23 and the sublamina 22. The

. tenonsy 26 are of the same cross sectional shape and size as the holes116 and are spaced to fit into the" holes 16. In the preferred form,holes 16 and tenons 26 have a rectangular cross section and are of suchdepth and such spacing as will provide a rigid connection between the lpanels. The tenons 26 are secured in the holes 16 preferably byA anadhesive such as an epoxy type resin. The

bottom wall of the cavity 25 is bonded to the overlapping portionA ofthe facing sheet 13 by the same or a similar adhesive.

The remaining portions of the edges of panels 11 and 21 haveconfigurations such that the two abut one another. The edges are bondedtogether by an adhesive such as an epoxyr resin to form the glue line31. This glue line is preferably extended upwardly in a somewhat*parallel direction to facing sheets 23 and then diagonally to theoutside corner 40. This provides a scarse greater area of bond betweenthe panels-.than would aV Straight "glue line extendingdirectly to thecorner 40:`

This entire arrangement of the inner cornerconstruc-y ance to shear1oads,the strength of the joint `is markedly.

increased. Theinterlocking facing sheets also prevent the edgs of thefacing sheets from being hooked by sharp objects.` Since the entire edge`of the inner facing sheet of panel 10 extends into the core material,it is impossibleto hook the inner edge of panel 10. It is alsoimpossible to hook portions of the inneredge of panel Z0. The strengthof `the jointlis increased by the innerv corner construction. `Inconventional inner structures, `a force-tending to part the joint exertsaforce in tension to the cores. This'corner construction by means of thebond between Vthe facing'sheets of overlapping portion ISand cavity `Zand the bond' between tenons Z6 and core 11 transmits the force on thecores to shear. vSince the cores are much more resistant-to shear'loadsthan tension loads, the joint is much stronger than conven-I tionaljoints.

The invention also has the advantage of penmitting the use of woodwithout danger of warpage due to moisture contactingthe wood. j Theresin facing skins 13A-and 23 cover all. normally exposed areas ofpanels having wood sublaminae., 'Ihisprotective covering permits theuseV of Wood with its high strength to weight ratio while at the sametimefprotecting the wood from moisture'in the surrounding,atmosphere. H1 c c i ffhe` use ofthe mortise and tenon type of interlockfor the innerfacing sheets provides a means of automatically aligning the panels. Theintertting of the parts eliminates the use of jigs or other alignmentmeans since they act in a manner similar to dowel or guide pins.

It will be seen that we have provided a strong and secure means forattaching two panels at an angle to each other. In its broadest aspectthis invention applies only to the inner corner construction 50. In thisrespect the outer corner construction can be varied without departingfrom the spirit of this invention. In this respect, the corner joint maybe used between panels having no outer facing sheets of any type. In thenarrower aspect, this invention applies to the combination inner cornerconstruction 50 and outer corner construction 40. Both of theseconstructions contribute to the strength of the entire panel cornerstructure.

While we have described a preferred embodiment of our invention, itshould be understood that other forms and embodiments can be madewithout departing from the principles thereof. Such modifications are tobe considered as included in the hereinafter appended claims unlessthese claims by their language expressly state otherwise.

We claim:

1. A corner construction which attaches two laminated panels disposedangularly to each other, each said panel having a cellular core and afacing sheet secured to each side of said core, which comprises a rstpanel having a plurality of aligned apertures spaced from the endextremity of said panel and extending through one of said cover sheetsand a part of said core, a second panel having a substantiallyrectangular cavity in the core thereof disposed immediately adjacent toa cover sheet and extending parallel thereto across the width of saidpanel and a plurality of spaced apertures in the cover sheet adjacent tosaid cavity, the apertures in said cover sheet dening a plurality oftenons which are spaced and sized so as to ht into and ll the saidapertures in said rst panel, and said panels in angular engagement suchthat the extreme end portion of said rst panel lies in and 6 lls thesaid rectangular cavity insaid second panel and the said tenons of saidsecondpanelh the aligned apertures in said rst panel. I

2. A corner construction for attaching two substantially at laminatedpanels to form a right angle, eachsaid panel having a low densitycellular core and higher' density facing sheets secured to eachsidesurfaceof said core, a cavity in the lcore of each said panelimmediately adjacent to the outer facing sheets of each said panel, saidcavity extending -across the width` of said panel and for a distanceinwardly from the edge extremities of said facing sheets,'the first ofsaid panels having a cavity immediately adjacent to the inner coversheetv extending across the width of said panel andfor a dis-l tanceinwardly from the inner surface of said inner facing sheet and for asubstantial distance parallel to the surface of said facing sheetthusdeining a substantially rectangular cavity in said core, the inneredge surfaces of the said cavity adjacent said outer'and said innercover sheets being joined by a` planar, diagonally disposed surface, andthe second of said panels having its inner end surface contoured tocomplement the core surface of said lirst panel when said panels areplaced in abutment..

' 3'. A panel .in accordance with claim 2 wherein the said cavityadjacent'to the said outer, facing sheets is filledwitha bead of shockresistant adhesive, andall contacting surfaces of said cover sheets andsaid cores are adhesively bonded together.

4. A corner construction in accordance with claim 2 wherein saidrstpanel is provided witha plurality of aligned apertures spaced fromthe end extremity -of said; panel and extending through one of saidcover sheets and` a part of said core, and said second panel is providedwith a plurality of spaced apertures in the cover sheet adjacent tosaid'cavity, the said cover sheet apertures dening a plurality of tenonswhich are spaced and sized to t into and ll the said apertures in saidrst panel when said panels are placed in abutment.

5. In an inner corner construction for attaching a first laminated panelto a second laminated panel, said panels being disposed at an angle toeach other, said laminated panels each having a body of low density,cellular, synthetic resin fill material and at least one high densityfacing sheet secured to said body at the inner sides of the angle formedby the panels thereby forming two adjacent edges, the improvementcomprising: a second panel having a cut out portion in said facing sheetand in the immediately adjacent low density, cellular, synthetic resinlill material of said edge of said second panel, a portion of said iirstpanel fitted into said cavity, said rst panel having a plurality ofholes at the juncture of said facing sheets of said panels, said holesextending through said facing sheet and -into said body of said rstpanel, protrusions on said facing sheet of said second panel extendinginto said holes and adhesively secured to said iill material of saidiirst panel, said facing sheet of said iirst panel being adhesivelybonded to said ll material of said second panel; the adjacent edges ofsaid bodies of low density, cellular, synthetic resin iill materialbeing shaped to t against each other, and said edges of said bodiesbeing secured to each other.

6. A corner construction for attaching a first laminated panel to asecond laminated panel, said panels being disposed at an angle to eachother, said laminated panels each having a body of ll material andfacing sheets secured to said body at the inner sides and the outersides thereby forming two adjacent edges, which comprises an innercorner construction having blind holes in said first panel spaced fromsaid edge of said first panel and extending through said facing sheetand into the body of said rst panel, protrusions on said edge of thefacing sheet of said second panel and extending beyond the immediatelyadjacent ll material of said second panel, said protrusions being ofsubstantially the same size and shape as said holes, received thereinand adhesively secured to the till material of said rst panel, theadjacent edges ofsaid bodies of ll material being shaped to fit againsteach other, said edges of saidy bodiesl being: secured to each other,and an outer corner construction having a cavity in said outer corner ofsaid ll material immediately adjacent said outer facing sheets, saidcavity extending` a distance toward the center and along the edge ofsaid sheets and said cavity being lled with a bead of shock resistantadhesive bonded to, said cores and to said outer facing sheets.

7. In a corner construction for attaching a rst laminated panel to asecond laminated panel, said panels being disposed at an angle to eachother, said laminated panels each having a body of ll material andfacing sheets secured to said body at the inner sides and the outersides thereby forming two adjacent edges, the improvement comprising aninner corner constructionr in which said edge of said second panel has acavity in said facing sheet and in the immediately adjacent ll material,a portion of said rst panel tted into said cut out portion, said tirstpanel having a plurality of holes spaced along the juncture of saidfacing sheets of said panels, said holes extending through said facingsheet and into said body of said irst panel, protrusions on said facingsheet of said second panel extending into said holes and adhesivelysecured to said fill material of said rst panel, and said edges of saidbodies being secured to each other, and an outer corner constructioncomprising said outer corner of said till material having a cavityimmediately adjacent said outer facing sheets, said cavity extending adistance toward the center and along the edge of said'` sheets, and saidcavity being filled with a bead of shockresistant adhesive bonded tosai-d cores and to said outer facing sheets.

8. In a corner construction for attaching a first laminated panel to asecond laminated panel, said panels, being disposed at an angle to eachother, saidlaminated panels each having a body of low density,cellular-, synthetic resin ll material and facing sheets secured tosaidbody. at the inner sides and the outer sides thereby forni,-t ingtwo adjacent edges, the improvement comprising; an inner cornerconstruction comprising,I said edgey ofmsaid, second panel having acavity in said facing sheetand, in, the immediately adjacent lowdensity, cellular, synthetic, resin till material, a portion of said rstpaneltted in to said cut out portion; said rst panel having a pluralityof, holes spaced along the juncture of said facing sheets of saidpanels, said holes extending through said facing sheet, and into saidbody of said rst panel, protrusions on said, facing sheet of said secondpanel extending in tQ said holesA and adhesively secured to said llmaterial of said first; panel, and said edges of said bodies beingssecured to each other, and an outer corner construction comprising saidouter corner of said low density, cellular, synthetic resin ll materialhaving a cavity immediately adjacent said outer facing sheets, saidcavity extending a distance toward the center and along the edge ofsaidl sheets-,and said cavity being filled with a bead of shockresistant. adhesive bonded to said cores and to said outer facinglsheets.

References Cited in the file of this patent UNITED STATES PATENTS yStearns Dec. 21, 1875' Jones 4.--- Jan. 17, 1956

